Ask HN: Logging Hours for Sprints, Useful?

This may have been discuss adnauseum before but here goes:

We run weekly sprint and require engineers to log hours on work accomplished to calculated actuals vs original estimates. As with any setup, engineers don't see the value in logging hours. Because, we aren't billing a customer directly I am a bit baffled on why we would also.

Is there any way to get velocity from a sprint based on Original Estimate and tickets/tasks completed without logging work hours? That is somewhat effective to get a worker KPI?